1. Field
Example embodiments relate to methods of fabricating a non-volatile memory device. More particularly, example embodiments relate methods of fabricating a flash memory device.
2. Description of the Related Art
A non-volatile memory device may maintain data stored therein even when the power supply is turned off. A flash memory device is a non-volatile memory device in which data may be electrically input or output. Flash memory devices may include a memory cell with a stacked structure. The stacked structure may include a tunnel insulation layer pattern, a charge storing layer pattern, a dielectric layer pattern, and a control gate sequentially stacked on a substrate.
In flash memory devices, data may be input or output by applying voltages to the control gate and the substrate to input electrons into the charge storing layer pattern or output electrons from the charge storing layer pattern. The electrons may be input into or output from the charge storing layer pattern through a tunnel insulation layer pattern that may be between the charge storing layer pattern and the substrate.
Repeated operation of a flash memory device may cause chemical bonds in the tunnel insulation layer pattern to break due to stresses generated therein. Accordingly, dangling bonds may be formed in the tunnel insulation layer pattern. Because electrons may be trapped in the dangling bonds, the threshold voltages of the memory cell may change. As a result, the flash memory device may have a deteriorated reliability.
In order to enhance the reliability, endurance, and/or data retention of a flash memory device, defects in the tunnel insulation layer may be cured. Thus, dangling bonds that may form in an interface between the tunnel insulation layer pattern and the substrate or in an interface between the tunnel insulation layer pattern and the charge storing layer pattern may be removed to reduce or prevent the trapping of electrons in the interfaces.
In order to remove the dangling bonds in the above interfaces, an annealing process using hydrogen may be performed on the flash memory device. However, hydrogen atoms may not penetrate certain layers of the flash memory device that cover the tunnel insulation layer pattern, e.g., a silicon nitride layer. Because the hydrogen atoms may be prevented or inhibited from reaching the tunnel insulation pattern, the annealing process may not remove the dangling bonds. Accordingly, the annealing process may not improve the characteristics of the tunnel insulation pattern.